Emily Dickinson Lexicon

UN-FIRM', a. [See Firm.]

1. Not firm; weak; feeble; infirm. Note. When we speak of the weakness of the human frame, we use infirm. When we speak of the weakness of other things, as a bridge, wall and the like, we say, it is unfirm.
2. Not stable; not well fixed. With feet unfirm. Dryden.